| 摘要 |
PURPOSE:To attain accurate adjusting operation even if brightness is not sufficient and the amplitude of a photographing signal is small by switching the circuit so that the gain of an amplifier circuit of the photographing signal controlled by an AGC circuit or the like is decreased at the automatic adjustment of white balance. CONSTITUTION:When the automatic adjustment is performed by a white balance circuit 10 with a command switch applied, a resistor for switching AGC sensitivity of an AGC circuit 2 is controlled so as to decrease automatically the amplifier gain of the photographing signal in comparison with the normal AGC operation. Thus, even if the brightness of the incident light from a filter or the like of a specific color to the image pickup element at automatic adjustment is not enough and the amplitude of the photographing signal is small, the excessive amplifier gain by the operation of the AGC circuit 2 is prevented, and the noise signal is not excessively included in each chrominance signal inputted to a comparator circuit 9 for automatic adjustment, then the automatic adjustment of accurate white balance is attained even under the condition with insufficient brightness. |
